What is the purpose of the extraction with H2SO4 and NH4OH in the chemical screening for alkaloids?

I - The extraction with H2SO4 is based on the ...

Question

What is the purpose of the extraction with H2SO4 and NH4OH in the chemical screening for alkaloids?

I - The extraction with H2SO4 is based on the fact that many alkaloids are soluble in an acidic medium.
II - The addition of NH4OH dilute to the acidic extract increases the pH, converting the alkaloids to their basic forms, which are soluble in CHCl3.
III - The extraction with CHCl3 is performed to transfer the alkaloids from the aqueous phase (alkaline extract) to the organic phase (CHCl3).
IV - The reduction of the volume of the chloroformic extract aims to concentrate the alkaloids present in the solution, facilitating subsequent detection and identification.
a) Only I and II are correct.
b) Only II and III are correct.
c) Only III and IV are correct.
d) I, II, III and IV are correct.

Ed · Answer

O objetivo da extração com H2SO4 e NH4OH na triagem química de alcaloides é separar os alcaloides presentes na amostra. A extração com H2SO4 é baseada no fato de que muitos alcaloides são solúveis em meio ácido. A adição de NH4OH diluído ao extrato ácido aumenta o pH, convertendo os alcaloides em suas formas básicas, que são solúveis em CHCl3. A extração com CHCl3 é realizada para transferir os alcaloides da fase aquosa (extrato alcalino) para a fase orgânica (CHCl3). A redução do volume do extrato clorofórmico tem como objetivo concentrar os alcaloides presentes na solução, facilitando a detecção e identificação subsequentes. Portanto, a alternativa correta é a letra d) I, II, III e IV estão corretas.

What is the purpose of the extraction with H2SO4 and NH4OH in the chemical screening for alkaloids? I - The extraction with H2SO4 is based on the ...

Farmacognosia, Fitoquímica e Fitoterapia

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PRÁTICA 8 - SCREENING QUÍMICO PARA ALCALÓIDES

Farmacognosia, Fitoquímica e Fitoterapia • Universidade Federal da BahiaUniversidade Federal da Bahia

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